The temporary flight restrictions that will greatly effect General aviation aircraft, and airlines don't go into effect until the 21st at 1230 local time, for one hour. but that means no aircraft are allowed to be in the air during that time. But the increased security for the next 5 days will be more of an issue to anyone flying.

I was in Chicago this past weekend. One can driver told us he is taking this weekend off. They shut down te majority of downtown and it's grid lock with cops every corner. I asked about possible protesters, and he said they expect them in the thousands easily.